TURBULENCE, PEBBLES AND PLANETESIMALS : THE ORIGIN OF MINOR BODIES IN THE SOLAR SYSTEM

Introduction

The Minor Bodies of the Solar System, including Asteroids, Trojans, Comets, and Kuiper Belt Objects, are leftover planetary building blocks called planetesimals that were once abundant in the solar nebula. Through collisions and the accretion of large grains, also known as pebbles, these bodies grew into planets.

Turbulence and Planetesimal Formation

The efficiency of planetesimal formation via a gravitational collapse of pebble clouds and the characteristics of the forming planetesimals are determined by the size distribution and local concentration of the largest grains. Both of these factors are regulated by gas turbulence.

However, turbulence itself is dependent on the abundance of small grains, as it regulates the ionization level and the radiative cooling process.

Project Goals

In this project, we will develop radically new types of numerical experiments focused on three stages of planetesimal formation, with the goal of achieving a self-consistent turbulence and pebble size distribution:

1. Development of Tools: We will create tools to measure the transport, diffusion, and collisions of dust grains for arbitrary MHD or Radiation Hydro disk simulations. This will help derive a consistent particle size distribution using a Coagulation Code and Machine Learning Techniques, which will provide consistent opacities and ionization rates to feed back into the turbulence simulation.

2. Implementation of a Tree-Solver: A tree-solver will be implemented to calculate the gravitational attraction among pebbles in self-consistent turbulence simulations. This will help identify the properties of pebble clouds that can undergo gravitational collapse.

3. Integration of an Implicit Solver: We will integrate an implicit solver for our Lagrangian Particle scheme to model the collapse of pebble clouds. This will not only derive a mass function and multiplicity but will also analyze the spin, shape, and compression of the forming planetesimals, comets, and asteroids by incorporating a model for elasticity and porosity.

Collaboration and Calibration

In close collaboration with our scientific community, we will calibrate our turbulence models and the planetesimal formation process based on observations of disks around young stars, as well as observational and laboratory data on Minor Bodies in the Solar System.